Neoseeker has a Speakers buyers guide up. If you're not an audiophile you might
not know what to look for. Check out what they have to say here.

Multimedia speakers have come a long way. Today's offerings are considerably
closer to midrange sound systems than they ever have been and the trend will
only continue in that direction. Digital music, convergence, and the Internet
have all but guaranteed that the PC will become a general purpose multimedia
device. Once upon a time PCs were only used to do work, then to play games,
and now have become powerful multimedia devices.